Task Force Turkey Earthquake Sequence 2023

The doublet of earthquakes in Turkey, February 6, 2023 devastated the Southeast of the country with deaths in the thousands. To understand this highly active and dangerous zone, this NatRiskChange Task Force looked into details of this rather anomalous event: The first main shock originated on a splay fault, propagated into the East Anatolian Fault Zone; hitting several big cities, such as Kahramanmaras or Gaziantep. The first big earthquake probably activated second one. To understand the relation of the two large earthquakes, this Task Force further investigated the aftershock sequence and found the Omori law fit decays. The shaking was perceived by the people and reports about the intensity still were filed. That allowed us to estimate the shaking. We introduced a new, yet unpublished method to interpolate for recordless places. By modeling the fault step wise, we found a mismatch between satellite images and expected magnitude which we could explain with deformation in different places subsequently. This mismatch between eastern and western side of the first fault is also mirrored in the reported intensities: The east reported higher shaking than expected, but also higher residuals of the static offset.

Please download the full report here.